An Active Gear Balancer for Torque Compensation

This paper presents a new concept of torque balancer for reducing the input torque fluctuation of a mechanism. The proposed active gear balancer consists of a differential gear train and a servomotor. By adjusting the control function of the servomotor, the input torque of the working mechanism can be balanced. Just like a gear reducer, the active gear balancer can be assembled and disassembled easily. An exact control function, which can completely eliminate the input torque fluctuation of the mechanism, is derived for the servomotor by an analytical method. Furthermore, both sequential and integrated optimization methods are developed for obtaining satisfactory trade-offs between the input torque fluctuations of the original motor and the servomotor. Additionally, learning control theory is validated to be a feasible and effective approach in controlling the servomotor to minimize the input torque fluctuation and to compensate the phase difference between the two input members. By taking a slider-crank mechanism as the working mechanism, four examples are given to illustrate the design procedures and to show their feasibilities.